Xt-27 wasn't just any robot. His identification plate read "Xt-27: the best, most modern robot". He was, indeed, the most up-to-date robot currently available, a product difficult to beat. Of course, this made him feel very proud. So much so, that when he saw other robots in the street, he would look at them with a certain air of superiority; he reserved his enthusiastic greetings for other xt-27s. "All robots should be like us xt-27s", he thought to himself. He was convinced that no new robot would be able to improve on the xt-27 model, and that the world would be a much better place if all robots were like himself. One day, he was walking along in bionic city, when a big yellow door suddenly appeared, about an inch in front of his piezoelectric optical sensors. He had no idea where the door had come from, but thanks to being an xt-27, his quick reactions allowed him to avoid walking straight into it. Intrigued, he pulled it open and went through the doorway. The door led to a fantastic city. All the city's inhabitants were xt-27s, and everything he saw there was mindblowing! Excited at having found his perfect city, he set to exploring the whole place, stopping from time to time to talk to people, telling them what a great thing it was to be an xt-27. Finally, he moved into his moulded fibreglass bubble , on the outskirts of the city. The days passed, but he suddenly realised that there was something about that city that he didn't like. As all the robots were xt-27s, it meant that no one had any reason to feel better or more up-to-date than anyone else, and, in fact, nobody did. No one looked down on others, and, if truth be told, he found that with the passing of time not even he felt special any more. On top of that, things became very boring. Everyone could do things equally well, which made it impossible for anyone to stand out from the crowd. Whenever he did anything which he thought brilliant, it turned out that the other robots had done exactly the same thing and at the same time. So xt-27 started to miss those varied little robots in his previous world. Each one had had its good and bad points, but that made them different and fun. He realised that he would much prefer to meet a clumsy-but-fun tp-4, and spend a while chatting with it, than see yet another xt-27. So he started searching for that big yellow door. It took him several days to find it, but finally he did. Just like before, it was standing in the middle of a normal street. He put his hand on the door and looked behind him, as if saying farewell to the city that had at first seemed so perfect. Then, he gave the door a joyful push… when he woke up, the xt-27 was on the ground, and some people were helping him to his feet. He looked around, and there was no yellow door at all. Instead there was an enormous shiny yellow robot. The xt-27 had bumped into it so violently that the jolt had made his circuits malfunction. The xt-27, surprised at not having managed to avoid the collision, looked carefully at that formidable-looking robot. He had never seen one like it. It seemed perfect in every way. It was taller and more powerful than any other, and its identification plate read: "Xt-28, the best, most modern robot". So they had done it. The seemingly impossible had happened. The xt-27s were no longer the best robots of all. Even so, our friend didn't feel the slightest sadness. Seconds earlier, when dreaming about the perfect city, he had learnt that he was very happy to be different, and that it was great to have hundreds of different robots; each one with its very own good and bad points. 
We cannot hope to be the best at everything, nor that everyone else be just like us. Every individual contributes something of value. 